TWI831331B - Organic electroluminescent devices and material thereof - Google Patents

Abstract

A material of the organic electroluminescent devices is provided. The material comprises a structure represented by following Formula (I): (I); wherein Ar ₁and Ar ₂are individually selected from substituted aryl group of 6 to 18 carbon, unsubstituted aryl group of 6 to 18 carbon, substituted aromatic ring or unsubstituted aromatic ring. The aromatic ring includes N atom. n is 2 or 3.

Description

Organic electroluminescent devices and materials

The present invention relates to an organic electroluminescent device and its materials, and in particular, to a novel material that can be used in the electron transport layer of an organic electroluminescent device.

Organic light-emitting diodes (OLEDs) are light-emitting elements manufactured using the principle of organic electroluminescence (OEL). The principle of luminescence is that under a certain electric field, the electron holes pass through the Hole Transport Layer (HTL) and the Electron Transport Layer (ETL) respectively, and then enter an organic substance (organic substance) with luminescent properties. luminescent layer). When electrons and holes recombine in this luminescent layer, an "excitation photon" is first formed, and then the energy is released and returned to the ground state. This released energy has Part of it is released in the form of light of different colors, making the OLED glow.

As the name suggests, the electron transport layer ETL's main function is to help electrons transport to the light-emitting layer to reduce the voltage and improve device efficiency. Currently, most of the electron transport layer materials commonly used in OLED components have small molecular structures, and their physical properties such as melting point _{Tm and} glass transition temperature _Tg are relatively low. In terms of component performance, they are prone to have low lifespan and poor efficiency. For example, commonly used structures include biphenanthroline (Bathophenanthroline, BPhen) and ET-Ph , which has a glass transition temperature (T _g ) of about 62-78°C, is easily deteriorated at the heating temperature of the process, has poor component life performance, and the luminous efficiency of the component still needs to be improved.

Therefore, developing related materials with better properties has always been the goal of relevant manufacturers.

The present invention provides a material for an organic electroluminescent device. Its compound structure and product characteristics are different from the prior art, and it is a novel invention.

According to an embodiment of the present invention, a material for an organic electroluminescent device is provided, which has a structure represented by the following chemical formula (I): (I).

In formula (I), Ar ₁ and Ar ₂ are each independently selected from substituted C ₆ to C ₁₈ aryl groups, unsubstituted C ₆ to C ₁₈ aryl groups, substituted heteroaryl groups containing N atoms, and unsubstituted C 6 to C 18 aryl groups. Substituted heteroaryl group containing N atoms, n is 2 or 3.

In one embodiment, Ar ₁ and Ar ₂ are each independently selected from , each A is independently selected from H, C _1-4 alkyl, benzene, naphthalene, quinoline, isoquinoline or pyridine.

In one embodiment, the material of formula (I) is a compound represented by any one of the following chemical formulas: ET1 ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET10 ET11 ET12 ET13 ET14 ET15 ET16 ET17 ET18 ET19 ET20 ET21 ET22 ET23 ET24 ET25 ET26 ET27 ET28 ET29 ET30 ET31 ET32 ET33 ET34 ET35 ET36 ET37 ET38 ET39 ET40 ET41 ET42 ET43 ET44 ET45 ET46 ET47 ET48 or . ET49 ET50

In one embodiment, the above material is used as an electron transport layer of an organic electroluminescent device.

According to another embodiment of the present invention, an organic electroluminescent device is provided, which includes a layered structure arranged in the following order: a transparent substrate, an anode layer, a hole transport layer, a light emitting layer, an electron transport layer and a cathode layer. The organic electroluminescent device is characterized in that its electron transport layer contains the above-mentioned materials.

In one embodiment, the organic electroluminescent device further includes a hole injection layer between the anode layer and the hole transport layer.

In one embodiment, the organic electroluminescent device further includes an electron injection layer between the electron transport layer and the cathode layer.

In one embodiment, the anode layer and the cathode layer of the organic electroluminescent device are respectively in contact with an external power source to form electrical paths.

Specifically, the novel structural material of the present invention is easier to prepare and purify than traditional electron transport materials, and has better device efficiency. When this material is used as the electron transport layer, the organic electroluminescent device produced has higher current efficiency and external quantum efficiency than organic electroluminescent devices using conventional materials.

The present invention provides a material for an organic electroluminescent device, which has a structure represented by the following chemical formula (I): (I).

In formula (I), Ar ₁ and Ar ₂ are each independently selected from substituted C ₆ to C ₁₈ aryl groups, unsubstituted C ₆ to C ₁₈ aryl groups, substituted heteroaryl groups containing N atoms, and unsubstituted C 6 to C 18 aryl groups. Substituted heteroaryl group containing N atoms, n is 2 or 3.

"Substituted" C ₆ to C ₁₈ aryl groups and heteroaryl groups containing N atoms in this article refer to H on the aryl/heteroaryl group consisting of one or more C ₁ -C ₄ alkyl groups, benzene, naphthalene ,quinoline ,isoquinoline or pyridine replaced. For example, suppose Ar ₁ is a benzene ring (C ₆ aryl), which has a total of 6 H (bondable positions), because one of the H positions is related to the pyrimidine in formula (I) connection, so there are only 5 H (bonding positions) left, then these 5 H can be replaced by C ₁ -C ₄ alkyl, benzene, naphthalene, quinoline, isoquinoline or pyridine.

Alternatively, Ar ₁ and Ar ₂ are each independently selected from benzene ring or pyridine , and each benzene ring can be optionally substituted by 1 to 5 C _1-4 alkyl groups, benzene, naphthalene, quinoline, isoquinoline or pyridine.

When the substituent itself has multiple bondable positions, it can be connected to the substituted structure at any bondable position. For example, quinoline There are a total of 7 bonding positions, and any one of these 7 positions can be connected to the substituted structure (C ₆ to C ₁₈ aryl, heteroaryl containing N atoms).

Materials of formula (I) can be obtained, for example, by the following two synthesis methods: Synthesis method 1 : Claisen-Schmidt condensation reaction (Intermediate A) Ring closing reaction (ET product) Synthesis method 2 : Claisen-Schmidt condensation reaction (Intermediate A) Ring closing reaction (Intermediate B) Suzuki Coupling (Intermediate B) Boric acid (ET product)

The above-mentioned synthesis method 1 only uses Claisen-Schmidt condensation reaction and ring closing reaction to synthesize products; while synthesis method 2 adds a step of Suzuki coupling reaction (Suzuki Coupling) to synthesize larger products. product of structure. The above three reactions are all common organic synthesis reactions in industrial applications. These reactions have short reaction times, are easy to prepare, generate few by-products, and are less difficult to purify, which are conducive to mass production and have low costs.

Each step of the above reaction is illustrated below through several application examples. However, it should be noted that the proportions and types of ingredients added to the compounds in the examples are only for demonstration purposes and are not intended to limit the present invention. Example 1

Synthesis of Intermediate A1 (A1)

Place 16.3 g of 4-(1-pyrenyl)phenylboronic acid, 8.6 g of 3-bromobenzaldehyde into a 500 mL three-neck flask, and mix with 200 ml of toluene. Weigh 12.6 grams of potassium carbonate into a beaker, add 65 ml of water to dissolve, and then add it to a three-necked flask. After adding 2.3 g of tetrakis(triphenylphosphine)palladium, the reaction was heated to reflux. After 5 hours of reaction, the temperature is lowered, the organic layer is extracted and separated, and the mixture is heated to remove low-boiling point solvents such as water. Add 40 grams of alumina and heat and stir for 1 hour. After filtering, drain the filtrate to obtain a thick liquid. After adding ethyl acetate to disperse the sample, a solid precipitated. After filtration, the solid was dried to obtain 9.13 grams of the finished product of intermediate A1, with a yield of 53%. Example 2

Synthesis of Intermediate A2 (A2)

Follow the synthesis procedure in compound A 1 , replace 4-(1-pyrenyl)phenylboronic acid with 3-(1-pyrenyl)phenylboronic acid, and replace 3-bromobenzaldehyde with 4-bromobenzaldehyde. Other reagents According to the same mole ratio adjustment, 9.82 grams of finished product A2 can be prepared with a yield of 57%. Example 3

Synthesis of Intermediate A3 (A3)

Follow the synthesis procedure in compound A1, replace 4-(1-pyrenyl)phenylboronic acid with 3-(1-pyrenyl)phenylboronic acid, and adjust other reagents according to the same molar ratio to prepare 7.92 grams of finished product A3. The rate is 46%. Example 4

Synthesis of Intermediate A4 (A4)

Following the synthesis procedure in Compound A 1 , replacing 3-bromobenzaldehyde with 4-bromobenzaldehyde, and adjusting other reagents according to the same molar ratio, 10.3 grams of finished product A4 can be prepared with a yield of 60%. Example 5

Synthesis of Intermediate A5-1 (A5-1)

Place 6.02 g of 3-(1-pyrenyl)phenylboronic acid, 4.8 g of 1-bromo-3-iodobenzene into a 250 mL three-neck flask, and mix with 75 ml of tetrahydrofuran. Weigh 3.82 grams of potassium tert-butoxide into a beaker, add 25 ml of water to dissolve, and then add it to a three-necked bottle. After adding 1.02 g of tetrakis(triphenylphosphine)palladium, the reaction was heated to reflux. After 7 hours of reaction, the temperature was lowered, and the organic layer was extracted and separated, and then concentrated under reduced pressure to remove the solvent. Add 250 ml of toluene, heat to remove the low boiling point solvent, add 20 grams of alumina, heat and stir for 1 hour, filter and drain the filtrate. Add 500 ml of n-hexane, heat and stir to dissolve the product, add 20 grams of alumina, heat and stir for 1 hour, filter and drain the filtrate. 6.58 grams of light yellow liquid A5-1 was obtained, with a yield of 90%. Example 6

Synthesis of Intermediate A5-2 (A5-2) (A5-1)

Place 6.54 g of A5-1 into a 250 mL three-neck flask and mix with 80 ml of tetrahydrofuran. Cool the reaction to -78°C. Slowly add 13 mL n-butyllithium dropwise. After the addition is complete, stir for about 20 minutes, while maintaining the temperature at -78°C. Slowly add 4 mL of triethyl borate dropwise, and slowly return to room temperature after the addition is complete. After reacting at room temperature for 3 hours, add 100 mL of 1N hydrochloric acid solution for extraction. Remove the organic layer and remove water with anhydrous magnesium sulfate. Concentrate and drain under reduced pressure. Add ethyl acetate: n-hexane = 100 mL: 50 mL and stir for 1 hour. After filtration, 2.93g of finished product A5-2 was obtained, with a yield of 49% . Example 7

Synthesis of Intermediate A5 (A5) (A5-2)

Follow the synthesis procedure in Compound A 1 , replace 4-(1-pyrenyl)phenylboronic acid with A5-2, replace 3-bromobenzaldehyde with 4-bromobenzaldehyde, and adjust other reagents according to the same molar ratio. , 3.82 grams of finished product A5 can be prepared, with a yield of 51%. Example 8

Synthesis of Intermediate B1 (A1) (B1)

Place 9.13 g of intermediate A1 into a 500-mL three-neck flask and mix with 90 mL of ethanol. Add 2.44 grams of potassium hydroxide, stir, and cool the reaction in an ice bath. A mixed solution of 4.32 grams of 1-(4-bromophenyl)ethanone and 30 ml of ethanol was added to the reaction, and the ice bath was continued for about 2 hours before returning to room temperature naturally. After reacting for about 19 hours, it was filtered. Add 3 grams of potassium hydroxide, 8.18 grams of 4-bromobenzamidine hydrochloride, 100 ml of ethanol and 200 ml of tetrahydrofuran to the solid, mix, and then heat to reflux. After 24 hours of reaction, the temperature was lowered, and the solution was concentrated under reduced pressure and drained. The solid was heated and stirred with 400 ml of ethyl acetate, and then filtered. The filtered solid was stirred with ethyl acetate and water, and the salts were removed by filtration to obtain a yellow solid. The solid was dried to obtain 10.09 g of the finished product of intermediate B1, with a yield of 63%. Example 9

Synthesis of Intermediate B2 (A1) (B2)

Follow the synthesis procedure in compound intermediate B1, replace 4-bromobenzamidine hydrochloride with 3-bromobenzamidine hydrochloride, and adjust other reagents according to the same molar ratio to prepare 9.24 grams of finished product intermediate B2. , yield 53%. Example 10

Synthesis of ET6 (A1) (ET6)

Place 4.21 g of intermediate A1 into a 250-mL three-neck flask and mix with 45 mL of ethanol. Add 1.12 grams of potassium hydroxide, stir, and cool the reaction in an ice bath. A mixed solution of 1.96 g of 3-acetylbiphenyl and 15 ml of ethanol was added to the reaction. The ice bath was continued for about 2 hours and then returned to room temperature naturally. After about 19 hours of reaction, it was filtered. Add 2.02 g of potassium hydroxide, 2.52 g of pyridine-3-formamidine hydrochloride, 50 ml of ethanol and 100 ml of tetrahydrofuran to the solid, mix, and then heat to reflux. After 24 hours of reaction, the temperature was lowered, and the solution was concentrated under reduced pressure and drained. The solid was heated and stirred with 200 ml of ethyl acetate, and then filtered. The filtered solid was stirred with ethyl acetate and water, and the salts were removed by filtration to obtain a yellow solid. The solid was dried to obtain 3.84 grams of ET6 finished product, with a purity of 96.84% and a yield of 58%. After sublimation purification, 1.82 grams of product was obtained with a purity of 99.72%.

¹ H NMR (400MHz, CDCl ₃ ): δ9.96(s, 1H), δ8.97(d, 1H), δ8.76(d, 1H), δ8.62(s, 1H), δ8.51( s, 1H), δ8.29-8.14(m, 7H), δ8.09(s, 2H), δ8.07-7.98(m, 3H), δ7.90(d, 3H), δ7.77(d , 3H), δ7.73-7.62(m, 4H), δ7.54-7.39(m, 4H).

MS (m/z): [M ⁺ ] calcd. C ₄₉ H ₃₁ N ₃ for, 661; found, 661 Example 11

Synthesis of ET5 (A2) (ET5)

Following the synthesis procedure of compound ET6, intermediate A1 is replaced by intermediate A2, and other reagents are adjusted according to the same molar ratio. 2.81 grams of finished product ET5 can be prepared with a purity of 98.52% and a yield of 47%. After sublimation purification, 1.23 grams of product was obtained with a purity of 99.81%.

¹ H NMR (400MHz, CDCl ₃ ): δ9.92(s, 1H), δ8.95(d, 1H), δ8.74(d, 1H), δ8.48(s, 1H), δ8.38( d, 2H), δ8.27-7.88(m, 14H), δ7.83-7.61(m, 7H), δ7.55-7.38(m, 4H).

MS (m/z): [M ⁺ ] calcd. C ₄₉ H ₃₁ N ₃ for, 661; found, 661 Example 12

Synthesis of ET7 (A4) (ET7)

Following the synthesis procedure of compound ET6, intermediate A1 is replaced by intermediate A4, and other reagents are adjusted according to the same molar ratio. 4.03 grams of finished product ET7 can be prepared with a purity of 99.65% and a yield of 61%. After sublimation purification, 2.04 grams of product was obtained with a purity of 99.82%.

¹ H NMR (400MHz, CDCl ₃ ): δ9.95(s, 1H), δ8.99(d, 1H), δ8.76(d, 1H), δ8.52(s, 1H), δ8.45( d, 2H), δ8.29-8.15(m, 6H), δ8.11(s, 2H), δ8.07-7.99(m, 3H), δ7.94(d, 2H), δ7.90(d , 2H), δ7.81-7.63(m, 6H), δ7.55-7.40(m, 4H).

MS (m/z): [M ⁺ ] calcd. C ₄₉ H ₃₁ N ₃ for, 661; found, 661 Example 13

Synthesis of ET8 (A3) (ET8)

Following the synthesis procedure of compound ET6, intermediate A1 is replaced by intermediate A3, and other reagents are adjusted according to the same molar ratio. 3.55 grams of finished product ET8 can be prepared with a purity of 95.66% and a yield of 53%. After sublimation purification, 1.7 grams of product was obtained with a purity of 99.85%.

¹ H NMR (400MHz, CDCl ₃ ): δ9.92(s, 1H), δ8.93(d, 1H), δ8.73(d, 1H), δ8.57(s, 1H), δ8.48( s, 1H), δ8.31-7.95(m, 14H), δ7.88-7.56(m, 9H), δ7.51-7.35(m, 3H).

MS (m/z): [M ⁺ ] calcd. C ₄₉ H ₃₁ N ₃ for, 661; found, 661 Example 14

Synthesis of ET9 (A2) (ET9)

Follow the synthetic procedure in compound ET6, replace intermediate A1 with intermediate A2, replace 3-acetylbiphenyl with 1-[4-(3-pyridyl)phenyl]ethanone, and use the same procedures for other reagents. By adjusting the number ratio, 2.24 grams of ET9 finished product can be prepared with a purity of 99.14% and a yield of 41%. After sublimation purification, 0.73 g of product was obtained with a purity of 99.92%.

¹ H NMR (400MHz, CDCl ₃ ): δ8.92(s, 1H), δ8.74(d, 2H), δ8.63(d, 1H), δ8.36(d, 4H), δ8.27- 8.14(m, 4H), δ8.10(s, 2H), δ8.06-7.98(m, 4H), δ7.96-7.83(m, 4H), δ7.79(m, 1H), δ7.72 (d, 2H), δ7.66(m, 2H), δ7.58-7.50(m, 3H), δ7.38(m, 1H).

MS (m/z): [M ⁺ ] calcd. C ₄₉ H ₃₁ N ₃ for, 661; found, 661 Example 15

Synthesis of ET10 (A3) (ET10)

Follow the synthetic procedure in compound ET6, replace intermediate A1 with intermediate A3, replace 3-acetyl biphenyl with 1-[4-(3-pyridyl)phenyl]ethanone, and use the same procedures for other reagents. By adjusting the number ratio, 3.8 grams of ET10 finished product can be prepared with a purity of 99.03% and a yield of 57%. After sublimation purification, 2.17 grams of product was obtained with a purity of 99.91%.

¹ H NMR (400MHz, CDCl ₃ ): δ8.90(s, 1H), δ8.73(d, 2H), δ8.62(d, 1H), δ8.57(s, 1H), δ8.37( d, 2H), δ8.28(d, 2H), δ8.24(d, 1H), δ8.20(d, 1H), δ8.15(d, 1H), δ8.10(s, 2H), δ8.07-7.96(m, 5H), δ7.92(d, 1H), δ7.88-7.81(m, 2H), δ7.75-7.62(m, 5H), δ7.54-7.49(m, 3H), δ7.39(m, 1H).

MS (m/z): [M+] calcd. C ₄₉ H ₃₁ N ₃ for, 661; found, 661 Example 16

Synthesis of ET11 (A4) (ET11)

Follow the synthetic procedure in compound ET6, replace intermediate A1 with intermediate A4, replace 3-acetylbiphenyl with 1-[4-(3-pyridyl)phenyl]ethanone, and use the same procedures for other reagents. By adjusting the ratio of Er number, 3.22 grams of ET11 finished product can be prepared, with a purity of 99.13% and a yield of 64%. After sublimation purification, 1.58 grams of product was obtained with a purity of 99.86%.

¹ H NMR (400MHz, CDCl ₃ ): δ8.95(s, 1H), δ8.77(d, 2H), δ8.64(d, 1H), δ8.48-8.43(m, 4H), δ8. 28-8.16(m, 4H), δ8.14(s, 1H), δ8.11(s, 2H), δ8.08-7.96(m, 4H), δ7.94(d, 2H), δ7.90 (d, 2H), δ7.83-7.75(m, 4H), δ7.53-7.60(m, 3H), δ7.45-7.40(m, 1H).

MS (m/z): [M ⁺ ] calcd. C ₄₉ H ₃₁ N ₃ for, 661; found, 661 Example 17

Synthesis of ET12 (A1) (ET12)

Follow the synthesis procedure of compound ET6, replace 3-acetyl biphenyl with 1-[4-(3-pyridyl)phenyl]ethanone, and adjust other reagents according to the same molar ratio to prepare 2.83 grams of ET12 finished product. , purity 95.98%, yield 43%. After sublimation purification, 1.32 grams of product was obtained with a purity of 99.48%.

¹ H NMR (400MHz, CDCl ₃ ): δ8.94(s, 1H), δ8.78(d, 2H), δ8.63(s, 2H), δ8.43(d, 2H), δ8.33- 8.15(m, 5H), δ8.13(s, 1H), δ8.10(s, 2H), δ8.07-7.98(m, 3H), δ7.98-7.87(m, 4H), δ7.78 (d, 4H), δ7.73-7.67(m, 1H), δ7.60-7.52(m, 3H), δ7.43-7.38(m, 1H).

MS (m/z): [M ⁺ ] calcd. C ₄₉ H ₃₁ N ₃ for, 661; found, 661 Example 18

Synthesis of ET17 (A5) (ET17)

Follow the synthetic procedure in compound ET6, replace intermediate A1 with intermediate A5, replace 3-acetyl biphenyl with 1-[4-(3-pyridyl)phenyl]ethanone, and use the same procedures for other reagents. By adjusting the ratio of Er number, 4.72 grams of ET17 finished product can be prepared, with a purity of 99.38% and a yield of 69%. After sublimation purification, 3.17 grams of product was obtained with a purity of 99.89%.

¹ H NMR (400MHz, CDCl ₃ ): δ8.93(s, 1H), δ8.73(d, 2H), δ8.63(d, 1H), δ8.39-8.34(m, 4H), δ8. 27-8.22(m, 2H), δ8.21-8.13(m, 2H), δ8.10(s, 2H), δ8.07-7.91(m, 7H), δ7.85-7.64(m, 9H) , δ7.60-7.51(m, 4H), δ7.41-7.36(m, 1H),.

MS (m/z): [M ⁺ ] calcd. C ₅₅ H ₃₅ N ₃ for, 737; found, 737 Example 19

Synthesis of ET41 (B1) (ET41)

Place 4.58 g of intermediate B1, 2.38 g of 2-naphthaleneboronic acid into a 250-mL three-neck flask, and mix with 60 ml of toluene. Weigh 2.85 grams of potassium tert-butoxide into a beaker, add 20 ml of water to dissolve, and then add it to a three-necked flask. After adding 0.36 g of tetrakis(triphenylphosphine)palladium, the reaction was heated to reflux. After 4.5 hours of reaction, cool down, pour about 200 ml of methanol to force out the solid, and then filter. Add 700 ml of toluene to the solid and heat to remove the low-boiling solvent. Add 20 grams of alumina, heat and stir for 1 hour and then filter. The filtrate was heated and distilled to remove the remaining 100 ml, and then cooled to room temperature for recrystallization. The recrystallized solid was heated and stirred with about 250 ml of tetrahydrofuran for 1 hour, and the remaining 100 ml was distilled off, then cooled and filtered, and the solid was dried to obtain 1.85 g of ET41 finished product, with a purity of 99.21% and a yield of 36%. After sublimation purification, 1.18 grams of product was obtained with a purity of 99.67%.

¹ H NMR (400MHz, CDCl ₃ ): δ8.89(d, 2H), δ8.66(s, 1H), δ8.45(d, 2H), δ8.34-8.12(m, 8H), δ8. 10(s, 2H), δ8.07-7.99(m, 3H), δ7.97-7.77(m, 17H), δ7.74-7.68(m, 1H), δ7.55-7.46(m, 4H) .

MS (m/z): [M ⁺ ] calcd. C ₆₄ H ₄₀ N ₂ for, 837; found, 837 Example 20

Synthesis of ET44 (B2) (ET44)

Follow the synthesis procedure in compound ET41 , replace B1 with B2, and replace 2-naphthylboronic acid with isoquinolin-4-ylboronic acid. Adjust other reagents according to the same molar ratio to prepare 1.64 grams of finished product ET44 with a purity of 99.13 %, yield 33%. After sublimation purification, and then recrystallization with toluene, 0.87 g of product was obtained with a purity of 99.72%.

¹ H NMR (400MHz, CDCl ₃ ): δ9.29(d, 2H), δ8.94(s, 1H), δ8.91(d, 1H), δ8.64(d, 2H), δ8.55( s, 1H), δ8.47(d, 2H), δ8.34(d, 1H), δ8.27-8.16(m, 5H), δ8.11(s, 2H), δ8.06-7.86(m , 10H) ,δ7.78-7.60(m, 11H).

MS (m/z): [M ⁺ ] calcd. C ₆₂ H ₃₈ N ₄ for, 839; found, 839 Example 21

Synthesis of ET45 (B1) (ET45)

Following the synthesis procedure of compound ET41 , replacing 2-naphthylboronic acid with phenylboronic acid, and adjusting other reagents according to the same molar ratio, 1.6 grams of finished product ET45 can be prepared with a purity of 96.71% and a yield of 29%. After sublimation purification, 0.83 g of product was obtained with a purity of 99.56%.

¹ H NMR (400MHz, CDCl ₃ ): δ8.84(d, 2H), δ8.65(s, 1H), δ8.43(d, 2H), δ8.35-8.14(m, 6H), δ8. 11(s, 2H), δ8.08-7.99(m, 3H), δ7.95-7.89(m, 3H), δ7.83-7.77(m, 6H), δ7.74-7.67(m, 5H) , δ7.52-7.45(m, 4H), δ7.43-7.35(m, 2H).

MS (m/z): [M ⁺ ] calcd. C ₅₆ H ₃₆ N ₂ for, 737; found, 737 Example 22

Synthesis of ET46 (B2) (ET46)

Follow the synthesis procedure in compound ET41 , replace B1 with B2, and replace 2-naphthaleneboronic acid with phenylboronic acid. Adjust other reagents according to the same molar ratio to prepare 1.5 grams of ET46 finished product with a purity of 97.67% and a yield of 34%. . After sublimation purification, 1.5 grams of product was obtained with a purity of 99.51%.

¹ H NMR (400MHz, CDCl ₃ ): δ9.01(s, 1H), δ8.76(d, 1H), δ8.65(s, 1H), δ8.42(d, 2H), δ8.36- 8.16(m, 6H), δ8.11(s, 2H), δ8.08-8.00(m, 3H), δ7.95-7.89(m, 3H), δ7.83-7.61(m, 11H), δ7 .53-7.46(m, 4H), δ7.43-7.35(m, 2H).

MS (m/z): [M ⁺ ] calcd. C ₅₆ H ₃₆ N ₂ for, 737; found, 737 Example 23 Synthesis of other ET compounds

The above Examples 1-22 introduce several synthesis examples of compounds of formula (I) (ET5-12, 17, 41, 44-46), but are not limited thereto. Those of ordinary skill in the art can use different starting materials and prepare different intermediates according to the synthesis methods of the above embodiments, and then synthesize different finished materials. For example, the preparation method of Example 1 can be followed, and different starting materials can be selected to perform the Suzuki coupling reaction to obtain different intermediates A. (Starting material 1) (Starting material 2) (Intermediate A)

Table 1 Comparison table of starting materials and products (intermediate A) of Suzuki coupling reaction Starting material 1 Starting material 2 CAS: 917380-57-5 A2 [Example 2] A3 [Example 3] CAS: 872050-52-7 A4 [Example 4] A1 [Example 1] A5-2 A5 [Example 7] A6 CAS: 918655-01-3 A7 A8

The intermediate A obtained in Table 1 above is combined with different aromatic ketones according to the synthesis method 1. and amidine compounds , different ET products can be produced as shown in Table 2 below. (Intermediate A) (ET product)

Various combinations of ET products are shown in Table 2:

Table 2 Comparison table between intermediate A and ET products Reactant Intermediate A aromatic ketones amidines ET products A1 CAS: 3112-01-4 CAS: 7356-60-7 ET6 [Example 10] A2 ET5 [Example 11] A3 ET8 [Example 13] A4 ET7 [Example 12] A5 ET13 A6 ET14 A7 ET15 A8 ET16 A1 CAS:90395-45-2 CAS: 206752-36-5 ET12 [Example 17] A2 ET9 [Example 14] A3 ET10 [Example 15] A4 ET11 [Example 16] A5 ET17 [Example 18] A6 ET18 A7 ET19 A8 ET20 A1 CAS:350-03-8 CAS: 206752-36-5 ET1 A2 ET2 A3 ET3 A4 ET4 A5 ET21 A6 ET22 A7 ET23 A8 ET24 A1 CAS:216576-92-0 CAS: 7356-60-7 ET25 A2 ET26 A3 ET27 A4 ET28 A5 ET29 A6 ET30 A7 ET31 A8 ET32 A1 CAS:112370-18-0 CAS: 7356-60-7 ET33 A2 ET34 A3 ET35 A4 ET36 A5 ET37 A6 ET38 A7 ET39 A8 ET40

In Tables 1 and 2, the number under the chemical formula is the CAS number, indicating that the drug with this structure can be purchased in the commercial market; the bracket [Example X] indicates that the detailed production process of the compound has been described in Example X. According to Table 1 and Table 2, a variety of different ET materials can be easily synthesized through different intermediates A, aromatic ketones and amidine compounds.

In addition, the material of formula (I) of the present invention can also be synthesized from intermediate A to intermediate B through the aforementioned synthesis method 2, and then combined with different boric acid compounds to perform a Suzuki coupling reaction, and different ET products can also be obtained.

Preparation of intermediate B (Intermediate A) (Intermediate B)

Preparation of ET product from intermediate B (Intermediate B) Boric acid (ET product)

Table 3 Comparison table of starting materials and intermediate B Intermediate A Intermediate B A1 CAS: 99-90-1 CAS: 26157-85-7 B2 [Example 9] A1 CAS: 22265-36-7 B1 [Example 8] A5 B3 A1 CAS: 3112-01-4 CAS: 22265-36-7 B4 A5 B5 A6 B6 A3 CAS: 90395-45-2 CAS: 26157-85-7 B7 A5 B8

Table 4 Comparison table between Suzuki coupling reaction intermediate B and ET products Intermediate B Boric acid ET products B1 CAS: 32316-92-0 ET41 [Example 19] CAS: 98-80-6 ET45 [Example 21] B7 CAS: 32316-92-0 ET42 B3 CAS: 191162-39-7 ET43 B2 CAS: 192182-56-2 ET44 [Example 20] CAS: 98-80-6 ET46 [Example 22] B4 CAS: 192182-56-2 ET47 B6 CAS: 192182-56-2 ET48 B5 CAS: 192182-56-2 ET49 B8 CAS: 191162-39-7 ET50

The detailed structures of various ET products conforming to formula (I) can be found in Table 5 below.

Table 5 ET product list ET1 ET2 ET3 ET4 ET5 ET6 ET7 ET8 ET9 ET10 ET11 ET12 ET13 ET14 ET15 ET16 ET17 ET18 ET19 ET20 ET21 ET22 ET23 ET24 ET25 ET26 ET27 ET28 ET29 ET30 ET31 ET32 ET33 ET34 ET35 ET36 ET37 ET38 ET39 ET40 ET41 ET42 ET43 ET44 ET45 ET46 ET47 ET48 ET49 ET50 Example 24 Measurement of glass transition temperature (T _g ) and triplet energy level (T ₁ )

For the electron transport layer material synthesized in the above embodiment, the glass transition temperature (T _g ) was measured with a differential scanning calorimetry (DSC) thermal analyzer (Differential Scanning Calorimetry, DSC), and the triplet energy level (T ₁ ) was measured with a fluorescence spectrometer. The results are presented in Table 6 below

Table 6 T _g and T ₁ of materials of Examples and Comparative Examples ET products T _g (℃) T ₁ (eV) ET5 116.65 1.86 ET6 113.33 1.86 ET7 119.34 1.87 ET8 110.79 1.86 ET9 131.54 1.87 ET10 122.68 1.86 ET11 134.72 1.87 ET12 125.79 1.86 ET17 134.67 1.87 ET41 138.16 1.86 ET44 152.46 1.86 ET45 136.48 1.86 ET46 131.54 1.86 BPhen (Comparative Example 1) 62 2.5 ET-Ph (Comparative Example 2) 78 2.41 α,β-AND (main material) - ~1.70eV

As can be seen from Table 6, the glass transition temperatures (T _g ) of the materials of the present invention are all higher than 110°C, and can reach a maximum of 152.46°C (ET44), which is higher than currently commonly used electron transport layer materials (Comparative Examples 1 and 2). The glass transition temperature has high thermal stability and is suitable for industrial processes. Its triplet energy level (T ₁ ≓ 1.90eV) is slightly higher than that of α,β-ADN main layer material (T ₁ ≓ 1.70eV). Compared with BPhen (Comparative Example 1, T ₁ ≓ 2.5eV), the triplet energy level of the material of the present invention is closer, and the triplet excitons in the electron transport layer are more easily transferred to the light-emitting layer, reducing the loss in transmission and increasing the efficiency of the light-emitting layer. The triplet excited state is fused to the singlet excited state ratio through a triplet-triplet annihilation (TTA) reaction. Example 25 component test data

Please refer to FIG. 1 , which illustrates a schematic structural diagram of the organic electroluminescent device 10 used in this embodiment. The organic electroluminescent device 10 of this embodiment is mainly prepared by vacuum evaporation, and includes a glass substrate 1, ITO 2 (anode layer), a hole injection layer 3 (hole injection layer, HIL), and a hole transport layer 4 ( hole transport layer (HTL), luminescent layer 5 (host luminescent material and guest luminescent material), electron transport layer 6 (electron transport layer, ETL) and cathode layer 7. The anode layer 2 and the cathode layer 7 are respectively in contact with an external power supply to form electrical paths. This embodiment uses this device to test the characteristics of the organic electroluminescent device of the present invention.

It should be noted that in actual application, the organic electroluminescent device of the present invention is not limited to the above-mentioned aspects, and the structure can be adjusted according to needs. For example, an electron injection layer (EIL) can be designed between the electron transport layer 6 and the cathode layer 7 , and a hole blocking layer can be designed between the electron transport layer and the light-emitting layer, or the holes can be omitted. Injection layer 3, the present invention does not limit the structure of the organic electroluminescent device.

The organic electroluminescent device of this embodiment is characterized in that its electron transport layer is compound ET of formula (I) of this case, and conventional hole transport layer materials BPhen and ET-Ph are used as comparative examples. Except for this, the materials used for other layers of the organic electroluminescent devices of the Examples and Comparative Examples are exactly the same, as detailed in Table 7 below:

Table 7 Materials of each layer of the organic electroluminescent device 10 structure Material Substrate 1 Glass Anode layer 2 Indium tin oxide ITO Hole Injection Layer (HIL) 3 2-TNATA (65nm) Hole Transport Layer (HTL) 4 NPB (15nm) Luminous layer 5 Host: α,β-ADN Guest: BD-1 5% (30nm) Electron Transport Layer (ETL)6 ET of the present invention or comparative example BPhen, ET-Ph: x% LiQ (25nm) cathode layer 7 LiF 1nm, Al 100nm

This device is a blue light OLED. The chemical structures of each material are as follows:

The test results of organic electroluminescent devices using various ET materials according to embodiments of the present invention, as well as traditional materials BPhen and ET-Ph as the electron transport layer are shown in Table 7 below:

Table 7 Characteristics of organic electroluminescent devices of Examples and Comparative Examples Example ETL Proportion QQ Voltage* (V) EL max (nm) EQE* CE* (Cd/A) 1 ET5 85% 15% 6.80 467 8.55% 13.83 2 ET6 85% 15% 6.62 467 9.06% 15.01 3 ET7 85% 15% 6.74 467 8.35% 14.27 4 ET8 85% 15% 7.33 467 8.47% 14.05 5 ET9 50% 50% 5.85 467 10.07% 16.28 6 ET10 85% 15% 5.70 467 10.07% 16.42 7 ET11 50% 50% 5.97 467 9.46% 15.80 8 ET12 50% 50% 6.27 467 9.98% 16.44 9 ET17 85% 15% 7.03 467 8.74% 14.25 Comparative example 1 BPhen 85% 15% 6.89 467 7.47% 11.94 Comparative example 2 ET-Ph 85% 15% 9.54 466 6.44% 10.50 *Measurement value at current density 100 mA/ ^cm2

As can be seen from Table 7, compared with organic electroluminescent devices using traditional electron transport layer materials BPhen and ET-Ph (Comparative Examples 1 and 2), the organic electroluminescent device using the electron transport layer material of the present invention has better performance in When the current density is 100 mA/ ^cm2 , the voltage is low and it is a low-resistance material.

Furthermore, the compound of formula (I) of the present invention has a pyrene (Pyrene) structure, and its triplet energy level (T ₁ ≓ 1.90eV) is slightly higher than that of the fluorescent host Anthracene structural material (T ₁ ≓ 1.70eV), which can increase the electric hole The function of transferring triplet excitons in the transmission layer to the emitting layer (EML) increases the proportion of triplet excited states in the emitting layer that are fused to singlet excited states through the TTA reaction, thereby improving device efficiency, so it can have higher external quantum efficiency (External Quantum Efficiency, EQE) and higher current efficiency (Current Efficiency, CE). For example, compared with a device using the traditional electron transport layer material BPhen, the EQE of a device using the ET material of the present invention is increased by up to 34.8% (7.47→10.07%), and the current efficiency is increased by up to 37.5% (11.94→16.42 Cd/A), there is significant progress.

In addition, the preparation method of the above-mentioned materials is simple, easy to synthesize and purify, has the potential for commercial application, and has industrial application value.

Although the present invention is described above with examples, these examples are not intended to limit the present invention. Those of ordinary skill in the art can make equivalent implementations or changes to these embodiments without departing from the technical spirit of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended patent scope.

1:Glass substrate

10: Organic electroluminescent device

2:ITO (anode layer)

3: Hole injection layer

4: Hole transport layer

5: Luminous layer

6:Electron transport layer

7:Cathode layer

Figure 1 is a schematic diagram of an organic electroluminescent device according to an embodiment of the present invention.

1:Glass substrate

10: Organic electroluminescent device

2:ITO (anode layer)

3: Hole injection layer

4: Hole transport layer

5: Luminous layer

6:Electron transport layer

7:Cathode layer

Claims (7)

A material for an organic electroluminescent device having a structure represented by the following chemical formula (I):

wherein Ar ₁ and Ar ₂ are each independently selected from a benzene ring or pyridine, and each benzene ring is selectively substituted by 1 to 5 C _1-4 alkyl groups, benzene, naphthalene, quinoline, isoquinoline or pyridine, n is 2 or 3. For example, the material described in item 1 of the patent application scope is a compound represented by any one of the following chemical formulas:

The material described in item 1 or 2 of the patent application is used as an electron transport layer for an organic electroluminescent device. An organic electroluminescent device, which includes a layered structure arranged in the following order: a transparent substrate, an anode layer, a hole transport layer, a luminescent layer, an electron transport layer and a cathode layer; the organic electroluminescent device is characterized by: The electron transport layer includes the material described in any one of items 1 to 3 of the patent application scope. For the device described in Item 4 of the patent application, a hole injection layer is further included between the anode layer and the hole transport layer. For the device described in item 4 of the patent application, an electron injection layer is further included between the electron transport layer and the cathode layer. For the device described in Item 4 of the patent application, the anode layer and the cathode layer are respectively in contact with an external power supply to form an electrical path.